Merge pull request #184 from php-school/center-menu

Center menu

Author: AydinHassan

src/Factory/MenuFactory.php

@@ -76,6 +76,7 @@ function (CliMenu $menu) use ($exerciseRenderer, $eventDispatcher, $exercise) {
             ->setExitButtonText('EXIT')
             ->setBackgroundColour($c->get('bgColour'))
             ->setForegroundColour($c->get('fgColour'))
+            ->setMarginAuto()
             ->setWidth(70)
             ->modifySelectableStyle(function (SelectableStyle $style) {
                 $style